1. Field of the Invention
The present invention relates to acoustic transducer technology, and more particularly to a dual-diaphragm acoustic transducer for converting sound waves to electrical signals.
2. Description of the Related Art
With the rapid development of the 4C electronics (computer, communication, consumer electronics and car industries), mobile communication products such as smart phone, Bluetooth headset and microphone have become one of the mainstreams. Due to the demand for higher tone quality of mobile communication products is increasing, an acoustic transducer for use in the aforesaid mobile communication products must have good sensitivity.
A relevant prior art acoustic transducer, for example, U.S. Pat. No. 8,104,354 discloses a capacitance sensor that comprises a substrate, a sensing device, a movable frame, a first electrode and a second electrode respectively mounted at the substrate corresponding to the sensing device and the movable frame, and some spring members connecting the movable frame and the sensing device. When a sound wave pressure acts on the sensing device, the sensing device will move vertically relative to the first electrode (see FIG. 8B of the prior art), causing a change of the capacitance value therebetween and a relative change of the voltage that is induced across the capacitance. However, this design adopts one single sensing device (one single diaphragm), and this single sensing device may be unable to sense a very small volume of sound, lowering the sensitivity. Increasing the sensitivity must increase the sensing area of the sensing device. However, increasing the sensing area will affect the arrangement of the configuration of the whole structure.